linux-kernel - [PATCH v2 16/16] libsubcmd: Avoid two path statics

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Message-Id: <20230526183401.2326121-17-irogers@google.com>
Date:   Fri, 26 May 2023 11:34:01 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        "Steven Rostedt (Google)" <rostedt@...dmis.org>,
        Ross Zwisler <zwisler@...omium.org>,
        Leo Yan <leo.yan@...aro.org>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Yang Jihong <yangjihong1@...wei.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH v2 16/16] libsubcmd: Avoid two path statics

Use a single stack allocated buffer and avoid 8,192 bytes in .bss.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/lib/subcmd/exec-cmd.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/tools/lib/subcmd/exec-cmd.c b/tools/lib/subcmd/exec-cmd.c
index 5dbea456973e..7739b5217cf6 100644
--- a/tools/lib/subcmd/exec-cmd.c
+++ b/tools/lib/subcmd/exec-cmd.c
@@ -36,38 +36,40 @@ static int is_absolute_path(const char *path)
 	return path[0] == '/';
 }
 
-static const char *get_pwd_cwd(void)
+static const char *get_pwd_cwd(char *buf, size_t sz)
 {
-	static char cwd[PATH_MAX + 1];
 	char *pwd;
 	struct stat cwd_stat, pwd_stat;
-	if (getcwd(cwd, PATH_MAX) == NULL)
+	if (getcwd(buf, sz) == NULL)
 		return NULL;
 	pwd = getenv("PWD");
-	if (pwd && strcmp(pwd, cwd)) {
-		stat(cwd, &cwd_stat);
+	if (pwd && strcmp(pwd, buf)) {
+		stat(buf, &cwd_stat);
 		if (!stat(pwd, &pwd_stat) &&
 		    pwd_stat.st_dev == cwd_stat.st_dev &&
 		    pwd_stat.st_ino == cwd_stat.st_ino) {
-			strlcpy(cwd, pwd, PATH_MAX);
+			strlcpy(buf, pwd, sz);
 		}
 	}
-	return cwd;
+	return buf;
 }
 
-static const char *make_nonrelative_path(const char *path)
+static const char *make_nonrelative_path(char *buf, size_t sz, const char *path)
 {
-	static char buf[PATH_MAX + 1];
-
 	if (is_absolute_path(path)) {
-		if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
+		if (strlcpy(buf, path, sz) >= sz)
 			die("Too long path: %.*s", 60, path);
 	} else {
-		const char *cwd = get_pwd_cwd();
+		const char *cwd = get_pwd_cwd(buf, sz);
+
 		if (!cwd)
 			die("Cannot determine the current working directory");
-		if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX)
+
+		if (strlen(cwd) + strlen(path) + 2 >= sz)
 			die("Too long path: %.*s", 60, path);
+
+		strcat(buf, "/");
+		strcat(buf, path);
 	}
 	return buf;
 }
@@ -133,8 +135,11 @@ static void add_path(char **out, const char *path)
 	if (path && *path) {
 		if (is_absolute_path(path))
 			astrcat(out, path);
-		else
-			astrcat(out, make_nonrelative_path(path));
+		else {
+			char buf[PATH_MAX];
+
+			astrcat(out, make_nonrelative_path(buf, sizeof(buf), path));
+		}
 
 		astrcat(out, ":");
 	}
-- 
2.41.0.rc0.172.g3f132b7071-goog